Hydrocarbon fluids such as oil and gas are found in subterranean portions of geological formations or reservoirs. Wells are drilled into these formations for extracting the hydrocarbon fluids. Wells may be completed in a variety of ways including open hole and cased hole configurations. The processes involved in completing well bores and producing hydrocarbons from them often require isolation of one or more zones from another. For example, the well bore may pass through multiple production zones. In these applications, it may be desireable to isolate the non-productive regions located between the production zones. In particular, the annular region on a well bore disposed between the well bore wall (or casing) and the string may need to be isolated.
A variety of packers have been developed to isolate such regions. For example, mechanical, inflatable, chemical and pneumatic packers may be used. Such packers may respond to hydraulic pressure by expanding to fill the annulus. Swell rubber packers have been used that rely on an elastomeric material such as rubber and its tendency to swell in presence of hydrocarbons. Such packers have been disclosed in U.S. Pat. Publication No. 2007/0151723 by Freyer. These packers expand to fill an annulus when comes in contact with the wellbore fluids and have the advantage of not relying on separate actuation means or moving parts.
When the elastomer comprising the swell packer expands, the mechanical properties of the elastomer deteriorate and the packer weakens. As a result, the elastomer becomes prone to failure when exposed to high differential pressures. This may result in extrusion of the elastomer along the pressure gradient and the loss of the annular seal.
Accordingly, some packers have been provided with rigid, solid collars or rings placed at either end of the swell packer. Such devices may not reliably prevent extrusion as the variable diameter of a well bore may leave room between the collar and the wellbore wall that could allow for a portion of the elastomer to be extruded into the annular region above or below the packer. Also, such solid collars limit the ability to deploy intelligent completions devices such as fiber optic lines, wirelines, communications devices, sensors, and other such devices as the solid collar does not allow for deployment of such devices through the annular region.
Accordingly, there is a need for an anti-extrusion device for a swell packer that may reliably fill the annular region and prevent or limit extrusion under relatively high differrential pressures. There is also a need for an anti extrusion device that is capable of use while deploying intelligent well completions devices in conjunction with a swell packer.